Equipoising or lifting arms have supported equipment, such as Steadicam® brand stabilized camera systems, since 1975. These arms typically consist of two serial parallelogram linkages (segments) connected by a central hinge, with each linkage generating a lifting force created by a resilient means. The proximal hinges of these arms, i.e. the hinges closest to the operator on each segment, are typically hinged to a robust load-supporting vest, worn by the operator, and ideally support virtually all of the weight of the payload camera stabilizer (or industrial tool), and permit low friction, finger-tip manipulation thereof—as if in zero gravity—within the volume of space defined by their lifting and extending range. Unfortunately, to date, this volume is considerably less than the volume of space accessible to the average human arm.
As used herein an “equipoising arm” is not limited to a lifting arm that has a uniform lifting force throughout its excursion, although such an arm is within the definition.
Camera stabilizers, such as ‘Steadicam®’ devices in so-called ‘high-mode’ (camera mounted on top), typically deliver a range of lens heights from approximately waist to head; or alternately from knees to waist height in so-called ‘low-mode’ (camera hanging below). The operator must stop work and the equipment must be physically altered to switch from high-mode to low-mode shooting. If the lifting range of the camera stabilizer arms could more closely match the gripping range of the average human arm, the switch from high to low-mode operating would likely be needed much less often, since the lens, in low mode for instance, could go continuously from knee level to above head height.
Attempts have been made to add a third lifting segment to these equipoising arms in order to augment their lifting range, but the results have been unsatisfactory. Conventional equipoising arm segments are hinged to swing laterally, starting from the proximal hinge at the vest. These hinges present functional difficulties when a third lifting arm segment is added. All three segments, each weighing several pounds, can swing capriciously, since they now form three sides of a horizontal four-bar linkage, which is unrestrained and often haphazardly obstructive to normal operating.
An additional problem occurs when three-segment arms are mounted to a vest, in particular to the back of the vest, behind the operator. Non-vertical orientation of the proximal hinge causes the payload to side-slip laterally and requires proportional restraint. An arm-angle adjusting mechanism is located between the support structure at the vest and the proximal hinge to address the problem. These arm-angle adjusting mechanisms are frequently fine-tuned on-the-fly for various operating conditions and maneuvers, so it can be desirable to have them within reach of the operator. If a three-segment arm were to be mounted behind the operator, these adjustments would typically be unreachable by hand.
Additionally, past attempts to incorporate a third lifting segment often caused the added third segment to move uncontrollably in a vertical plane—locking up or down as the torque of the next section capriciously powers or de-powers the previous one.
What is needed is a way to increase the lifting range of an equipoising arm to more closely match the human ‘gripping range’ while minimizing degradation of functionality or performance.
What is needed is also a way to add a third lifting segment to an equipoising arm and still be able to adjust the arm's angular attitude on-the-fly, relative to the support structure of the vest.
Further needed is a way to provide a back-mounted, lifting segment for an equipoising arm, that does not require the entire assembly to be hinged for lateral movement at the mounting point and that allows arm-angle adjustments to be made within relatively easy reach.
Also, what is needed is a means to adjust the horizontal location of such a lifting segment for operators of varying girth; and also to switch it to either side of an operator for right-side vs. left-side operation.